Using a Chrome plugin for SSH is taking unnecessary risks.
What kind of risks are you concerned about? It's a sandboxed NaCl plugin with a strict CSP that runs OpenSSH. I suppose you could get concerned about key security (since they're stored in an html5 filesystem), but you should really have a passphrase on those anyway. If you can't hack it in a way where ctrl-alt-f1 will get you to a genuine linux getty, running standard GNU/Linux...
Developer mode lets you do exactly this. Crouton just gives you a pleasant way of running a full Ubuntu install.edit: I agree that vpn support is a huge disadvantage right now.